8 markers cost $13.68. Which equation would help determine the cost of 3 markers?
Explanation: There are several equations that could help determine the cost, each with a slightly different approach. We know the cost of 8 markers. We want to know the cost of 3 markers. We can write the numbers of markers as a proportion: $\dfrac{8}{3}$ We know 8 markers costs $13.68. We can let $x$ represent the unknown cost of 3 markers. The proportion of these costs can be expressed as: $\dfrac{\$13.68}{x}$ The cost changes along with the number of markers purchased, and so the two proportions are equivalent. $\dfrac{8}{3} = \dfrac{\$13.68}{x}$